Our invention relates to single phase aqueous surfactant-free nontoxic air freshening compositions and wick-containing air freshening devices using such compositions.
Conventional liquid air fresheners generally comprise a reservoir containing a mixture which may be a true solution, a colloidal solution or a microemulsion of a perfume with a solvent into which dips a wick which is connected to an emanating surface. The perfume mixture travels up the wick to the emanating surface from which the perfume evaporates and freshens the surrounding atmosphere. Perfumes used in those air fresheners are generally oils and are therefore generally insoluble in water in the absence of any other agents. Systems in which the perfume solution is aqueous based therefore always contain a surface active agent which solubilizes the perfume in water. The amount of surfactant has to be quite high, for instance, 10-15% or more by weight based on the total composition.
The surfactants used in such compositions are conventional surfactants, generally anionic surfactants such as alkyl benzene sulfonates and lauryl sulfates. Nonionic surfactants have also been used, but they are more expensive and tend to depress the perception of the perfume odor. These surface active agents are all nonvolatile, and they therefore do not evaporate from the emanating surface. The concentration of surfactant in the emanating surface therefore gradually increases, and the presence of surfactant impedes the progress of perfume in the wick and also prevents the perfume emanating as it should.
Most aqueous based systems also contain a cosolvent in addition to the perfume and surfactant. Examples of cosolvents are ethanol and diethylene glycol monoethyl ethers (DEGMEE). Such compositions always contain a surfactant and therefore suffer the same disadvantages as described above.
Some liquid air fresheners contain little or no water and so are free of surfactant. For example, a solution of perfume in DEGMEE having the structure: 
and water is stable as a single phase provided the amount of water is low, for example, below 20% when the amount of perfume is about 10% by weight. Since these compositions cannot tolerate high amounts of water, they tend to be expensive.
U.S. Pat. No. 3,945,950 (incorporated by reference herein) describes solid air freshener compositions, which suffer from different problems to the air fresheners comprising liquid compositions with which our invention is concerned. The solid compositions contain perfume, a diethylene glycol monoalkyl ether and a gelling agent, which is a surface active fatty acid soap or metal salt thereof and an inert liquid. Water is sometimes included in the compositions as some or all of the inert liquid, but only in small amounts of 4% by weight.
In U.S. Pat. No. 4,663,081 issued on May 5, 1987 (the specification for which is incorporated by reference herein), it is indicated that diethylene glycol monobutyl ether (DEGMBE) having the structure: 
can, when containing dissolved perfume, incorporate a surprisingly large amount of water compared to other glycol ethers and is therefore more cost effective. It is further indicated in U.S. Pat. No. 4,663,081 that the mixture of DEGMBE and water also has very suitable volatility properties and has a beneficial effect on the rate of emanation of the perfume. It is further indicated in U.S. Pat. No. 4,663,081 that the composition containing the DEGMBE generally comprises between 5 and 30% by weight of perfume; usually between 8 and 20% by weight of perfume and often 10% by weight. It is further indicated in U.S. Pat. No. 4,663,081 that the amounts of perfume in compositions containing DEGMBE affect the amount of water that can be mixed into the solution before a phase separation occurs. It is stated that, for example, when the concentration of perfume in the solution is 10% by weight then the maximum amount of water that can be incorporated in a one phase solution is about 55% by weight, and for a perfume solution at 20% concentration, the maximum amount of water is about 40% by weight.
It is further indicated in U.S. Pat. No. 4,663,081 that the perfume may be any of the perfumes conventionally used in air fresheners and that xe2x80x9cthe identity of the perfume makes little difference to the behavior of the solvent system. It is further indicated in U.S. Pat. No. 4,663,081:
xe2x80x9cSolutions of perfume in various glycol ethers of varying concentration were loaded with water until phase separation occurred. The maximum amounts of water tolerated in systems at various perfume concentrations for the glycol ethers tested is shown in Table 1.
As can be seen from the table DEGMBE can tolerate a far larger amount of water at a specified perfume concentration than any of the other glycol ethers.xe2x80x9d
For the purposes of the foregoing table and for use throughout the instant application, the following terms are defined:
DEGMEE: the compound having the structure: 
DEGDME: the compound having the structure: 
TPGMME: the compound having the structure: 
PGMPE: the compound having the structure: 
PGMME: the compound having the structure: 
DPGMME: the compound having the structure: 
PGMBE: the compound having the structure: 
DEGMBE: the compound having the structure: 
PGMEE: the compound having the structure: 
It is set forth at column 4, lines 15-17 of U.S. Pat. No. 4,663,081:
xe2x80x9cAs can be seen from the table DEGMBE can tolerate a far larger amount of water at a specified perfume concentration than any of the other glycol ethers.xe2x80x9d
In view of toxicity problems associated with DEGMBE having the structure: 
it has become apparent that a substitute for the system set forth in U.S. Pat. No. 4,663,081 is needed.
It is an object of our invention to provide such substitution means.
PCT Application No. 97/45516 published on Dec. 4, 1997 discloses and claims a phase-stable liquid refreshment and cleaning composition comprising:
(a) butoxy propoxy propanol; or other alkoxylated alkoxy propanol solvent (defined according to one of the structures: 
(b) water;
(c) optionally, a minor amount of nonionic surfactant; and
(d) an effective, phase stabilizing amount of a member selected from the group consisting of alkyl sulfate surfactant, alkyl ethoxy sulfate surfactant and mixtures thereof.
However, the PCT Application No. 97/45516 does not teach the problems solved by our invention.
Our invention is directed to a single phase aqueous surface-active agent-free air freshening composition characterized in that it is (a) nontoxic; (b) nonmutagenic; and (c) environmentally friendly, consisting essentially of:
(i) 30-70 weight percent water;
(ii) 5-20 weight percent of a fragrance composition wherein at least 60% of its composition consists of one or more substances having a C log10 Pxe2x89xa62.5 and no more than 40% of any of the components of the perfume composition has a C log10 P in the range of 2.5 less than C log10Pxe2x89xa67.5; and
(iii) 30-60 weight percent of a mixture of two glycol ether compounds, one of which is dipropylene glycol monomethyl ether having the structure: 
and the other of which is a compound defined according to the structure: 
wherein R is n-propyl or n-butyl. As is evident from reading the specification, any shortfall of ingredients as set forth by the percentages herein are readily made up by the addition of water, i.e., Qs to 100%.
A second embodiment of the invention provides a stain removal wipe with the components set forth hereinabove. More specifically, the wipes contain a mixture of (i) dipropylene glycol methyl ether and (ii) propylene glycol propyl ether or propylene glycol butyl ether in an aqueous solution. Fragrance is also included at a level of from about 0.01 to about 10 weight percent of the total solution weight, preferably from about 0.05 to about 8 and most preferably from about 0.1 to about 5 weight percent.
Optionally, a preservative is included in the aqueous solution. The total level of preservative is less than or equal to 1 weight percent of the aqueous solution. Suitable preservatives include, but are not limited to, methyl/ethyl/propyl/butyl paraben, EUXYL(copyright) K400, trademark of Schulke and Mayr GmbH of the Federal Republic of Germany and GERMALL(copyright) 11, trademark of ISP Chemicals Inc. of Chatham, N.J.
Also optionally included in the solution are chelators at a level of from about 0.01 to about 0.3 weight percent, preferably from about 0.05 to about 0.25 and most preferably at a level of about 0.2 weight percent. Suitable chelators include EDTA, and DEQUEST(copyright) phosphonate, trademark of Solutia Inc. of St. Louis, Mo.
The wipes of the present invention contain little or no surfactant or emulsifier materials. The wipes will contain less than 0.1 weight percent surfactant or emulsifier, preferably less than 0.05 weight percent of the aqueous solution and in a most preferred embodiment, no surfactant or emulsifier will be present.
The advantage of the wipes of the present invention is that the highly aqueous, low solvent, little or no surfactant system of the present invention is that it is capable of retaining the fragrance in solution. A further advantage of the wipes is the lack of residue after use and yet the wipe still has good performance and fragrance.
The wipe itself is preferably made of a non-woven material made from polyethylene, polypropylene, polyesters including polyester terphthalate and blends and copolymers of these materials. The wipe typically contains up to about 10 weight percent aqueous solution as described hereinabove, preferably from about 0.1 to about 8 and most preferably from about 1 to about 5 weight percent solutions.
The n-octanol/water partitioning coefficient of a perfume material indicated by the term xe2x80x9cPxe2x80x9d is the ratio between its equilibrium concentrations in n-octanol and in water. The perfume materials used in our invention have an n-octanol/water partitioning coefficient xe2x80x9cPxe2x80x9d of between about 1 and about 107.5 with at least 60% of the perfume components having a partitioning coefficient of between about 1 and about 102.5. Since the partitioning coefficients of the perfume compositions of this invention have values of between about 1 and about 107.5, they are more conveniently given in the form of their logarithm to the base 10, log10 P. Thus, the perfume materials useful in the practice of our invention have a log10 P of between about 1 and about 7.5 as indicated, supra, wherein 60% of the components of the perfume composition have a log10 P of between about 1 and about 2.5 as indicated, supra.
The log10 P of many perfume ingredients have been reported; for example, the Pomona 92 database, available from Daylight Chemical Information Systems, Inc. (Daylight CIS), Irvine, Calif., contains many, along with citations to the original literature. However, the log10 P values are most conveniently calculated by the xe2x80x9cCLOGPxe2x80x9d program, also available from Daylight CIS. This program also lists experimental log10 P, values when they are available in the Pomona 92 database. The xe2x80x9ccalculated log10 Pxe2x80x9d is determined by the fragment approach of Hansch and Leo (Comprehensive Medicinal Chemistry, Volume 4, C. Hansch, P. G. Sammens, J. B. Taylor and C. A. Ramsden, Editors, page 295, Pergamon Press, 1990, incorporated by reference herein). The fragment approach is based on the chemical structure of each component of the perfume material and takes into account the numbers and types of atoms, the atom connectivity and chemical bonding. The calculated log10 P values, which are the most reliable and widely used estimates for this physicochemical property, are preferably used instead of the experimental log10 P values in the selection of perfume materials useful in the practice of our invention.
More specifically, the perfume materials useful in the practice of our invention having a C log10 Pxe2x89xa62.5 are as follows:
For the purposes of our invention, the compounds defined according to the structure: 
wherein R is n-propyl or n-butyl, are shown by the symbol: [PnR].
The range of weight ratios of the dipropylene glycol monomethyl ether having the structure: 
varies from about 1:1 up to about 5:1.
The following example illustrates the invention, but the invention is only limited by the claims.